Developers should be able to specify grid column sort config property which is different from column field property.For instance, when listing products, my view model may have CategoryName property mapped from EF entity navigation property Category.Name using AutoMapper, while my sorting will use "Category.Name" on the server side.Example config could be like: 
columns[{title:"Category",field:"CategoryName",sort:"Category.Name"}]

This will allow me to flatten my view model without loosing sorting functionality.

The interface for PromptOptions does not extend DialogOptions like it should. I added it into my definition file, and it compiles and works fine when testing.

    interface PromptOptions extends DialogOptions {
        name?: string;
        messages?: PromptMessages;
    }

R2 2017 release finally add a new KendoListBox component.

However, It lack some features, available in dropdownlist, like filter and item grouping who prevent me to use it for huge item list.

..,or make it at least optional when using grouped column headers. Scenarios with many or repeating column titles would extremely benefit from this. 

A status-specific control would support max, min, targets, warning levels, etc and not be bound only to percentages as I see in the screenshots of http://www.telerik.com/support/demos or in the other dashboard sample. 
An example of this is:
http://www.oracle.com/webfolder/technetwork/jet/jetCookbook.html?component=home&demo=rootVisualizations_childGauge

Other vendors offer visual representations and better access to what controls are available and how to quickly use them in different scenarios. I cannot find any visual such as http://www.oracle.com/webfolder/technetwork/jet/jetCookbook.html?component=home&demo=all which nicely highlights what each control looks like from an index perspective.
Furthermore, the code in a cookbook should be copy and paste and not have dependencies on hidden helper classes.

Kendo UI pivotgrid should have a way to customize the filters.  Specifically have a date picker for date fields and a date range.  But something so we can override what the default is.

I am trying to use the DropDownList and find this level of documentation:

 <div class="demo-section k-content">
    <h4>Products</h4>
    @(Html.Kendo().DropDownList()
          .Name("products")
          .DataTextField("ProductName")
          .DataValueField("ProductID")
          .DataSource(source => {
              source.Read(read =>
              {
                  read.Action("GetProducts", "Home");
              }); 
          })
          .HtmlAttributes(new { style = "width: 100%" })
    )
</div>

The only other source file is a simple Controller Action method to return a result. There is no indication of what type of data is to be returned by the read.Action("GetProducts", "Home"); 

What fields are required in the data?
What field or fields are passed back to the Controller on Submit?
Is it JSON?
Is it in a wrapper like the Grid uses?

It is issues like this that make ALL the Telerik products difficult to use, and makes me consider using other tools. I think it lowers the value of the tools when Telerik appear to be happy that documentation of this level exists and users have to find answers and working real life examples on sites such as StackOverflow.

We want to create a generic Virtual Kendo DropDownList and use it where ever necessary in the entire project.
For that we would need to know the control id in valuemapper and parametermap. Please give us the access to that.

Thank you!

It would be nice to apply known Excel formatting options to our export cells. For instance, we'd like to be able to rotate a cells content 90 degrees, which Excel allows, but we aren't allowed to add that custom formatting because Kendo's export doesn't handle it.

The option in the Kendo Spreadsheet to show the unmarked values when a filter is applied instead to reset it by pressing the Clear button

It's convenient for users who use older version of Kendo UI

It would bei nice if the gantt would support Auto Height like Grid is doing and is only rendering the Height for the used elements, when you define no addiotional height property.

Splitter bar - animation when collapsing and expanding 
Would enhance a more graceful splitter widgets actions  

Kendo UI Chrome Inspector not finding elements in iframe. if possible there should be provision to select any kendo element from DOM and check kendo UI inspector.

When changing the bounds of a shape, especially changing the X & Y position allow the new value to be set with animation. 

The kendo.drawing.TooltipOptions do not provide a 

show { duration: [time]} 

option that will allow showing the tooltip for a certain duration of time, after which the tooltip will disappear automatically.

Can this be added?

Work like à tree view, but display as an organisation chart to see a company hierachy

Since aggregation causes data to change when using a date axis (new minimums and maximums), provide a way to retrieve the new minimums and maximums for each series plotted on a graph.

Data aggregation is not always desired with date data.  Scatter plots do not work well with dates.  I want to map every point of data I have without having them aggregated in different BaseUnitSteps.

I'd like an option to turn off data aggregation for date series.